Liquid crystal composition and liquid crystal display device

ABSTRACT

The disclosure shows a liquid-crystal composition having at least one or suitable balance regarding at least two of characteristics such as high maximum temperature of nematic phase, low minimum temperature thereof, small viscosity, suitable optical-anisotropy, large dielectric-anisotropy, large specific resistance, high stability to ultraviolet light and heat; and an AM device including the composition and having short response time, large voltage holding ratio, large contrast ratio or long life. The liquid-crystal composition has the nematic phase and contains a specific compound having small optical-anisotropy and large positive dielectric-anisotropy as first component, a specific compound having small viscosity as second component, and may contain a specific compound having high maximum temperature or small viscosity as third component, a specific compound having large positive-dielectric anisotropy as fourth component or a specific compound having negative dielectric-anisotropy as fifth component, and a liquid-crystal display device includes the composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serialno. 2015-149488, filed on Jul. 29, 2015. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition, a liquid crystaldisplay device including the composition, and so forth. In particular,the invention relates to a liquid crystal composition having a positivedielectric anisotropy, and an active matrix (AM) device that includesthe liquid crystal composition and has a mode such as a TN mode, an OCBmode, an IPS mode, an FFS mode or an FPA mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystal molecules includes a phase change (PC)mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode,an electrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode, a fringe field switching (FFS) mode and afield-induced photo-reactive alignment (FPA) mode. A classificationbased on a driving mode in the device includes a passive matrix (PM) andan active matrix (AM). The PM is classified into static and multiplexand so forth. The AM is classified into a thin film transistor (TFT), ametal insulator metal (MIM) and so forth. The TFT is further classifiedinto amorphous silicon and polycrystal silicon. The latter is classifiedinto a high temperature type and a low temperature type based on aproduction process. A classification based on a light source includes areflective type utilizing natural light, a transmissive type utilizingbacklight and a transflective type utilizing both the natural light andthe backlight.

The liquid crystal display device includes a liquid crystal compositionhaving a nematic phase. The composition has suitable characteristics. AnAM device having good characteristics can be obtained by improvingcharacteristics of the composition. Table 1 below summarizes arelationship in two characteristics. The characteristics of thecomposition will be further described based on a commercially availableAM device. A temperature range of the nematic phase relates to atemperature range in which the device can be used. A preferred maximumtemperature of the nematic phase is approximately 70° C. or higher, anda preferred minimum temperature of the nematic phase is approximately−10° C. or lower. Viscosity of the liquid crystal composition relates toa response time of the device. A short response time is preferred fordisplaying moving images on the device. A shorter response time even byone millisecond is desirable. Accordingly, a small viscosity of thecomposition is preferred. A small viscosity at a low temperature isfurther preferred. An elastic constant of the composition relates to acontrast of the device. In order to increase the contrast of the device,a large elastic constant in the composition is further preferred.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics of General Characteristics of AM No. Composition Device1 Wide temperature range of a Wide usable temperature range nematicphase 2 Small viscosity Short response time 3 Suitable opticalanisotropy Large contrast ratio 4 Large positive or negative Lowthreshold voltage and dielectric anisotropy small electric powerconsumption Large contrast ratio 5 Large specific resistance Largevoltage holding ratio and large contrast ratio 6 High stability toultraviolet Long service life light and heat 7 Large elastic constantLarge contrast ratio and short response time

An optical anisotropy of the composition relates to a contrast ratio inthe device. According to a mode of the device, a large opticalanisotropy or a small optical anisotropy, more specifically, a suitableoptical anisotropy is required. A product (Δn×d) of the opticalanisotropy (Δn) of the composition and a cell gap (d) in the device isdesigned so as to maximize the contrast ratio. A suitable value of theproduct depends on a type of the operating mode. In a device having amode such as TN, a suitable value is approximately 0.45 micrometer. Inthe above case, a composition having the large optical anisotropy ispreferred for a device having a small cell gap. A large dielectricanisotropy in the composition contributes to a low threshold voltage, asmall electric power consumption and a large contrast ratio in thedevice. Accordingly, the large dielectric anisotropy is preferred. Alarge specific resistance in the composition contributes to a largevoltage holding ratio and the large contrast ratio in the device.Accordingly, a composition having the large specific resistance at roomtemperature and also at a temperature close to the maximum temperatureof the nematic phase in an initial stage is preferred. The compositionhaving the large specific resistance at room temperature and also at atemperature close to the maximum temperature of the nematic phase afterthe device has been used for a long period of time is preferred.Stability of the composition to ultraviolet light and heat relates to aservice life of the liquid crystal display device. In the case where thestability is high, the device has a long service life. Suchcharacteristics are preferred for an AM device used in a liquid crystalprojector, a liquid crystal television and so forth.

A composition having a positive dielectric anisotropy is used in an AMdevice having the TN mode. In an AM device having the VA mode, acomposition having a negative dielectric anisotropy is used. Acomposition having the positive or negative dielectric anisotropy isused in an AM device having the IPS mode or the FFS mode. In an AMdevice having the polymer sustained alignment (PSA) mode, a compositionhaving the positive or negative dielectric anisotropy is used. Examplesof the liquid crystal compositions having a positive dielectricanisotropy are disclosed in Patent literature No. 1 or No. 2 describedbelow.

CITATION LIST Patent Literature

-   Patent literature No. 1: WO 1996/011897 A.-   Patent literature No. 2: JP H10-204016 A.

SUMMARY OF INVENTION Technical Problem

One of aims of the invention is to provide a liquid crystal compositionsatisfying at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of the nematicphase, a small viscosity, a suitable optical anisotropy, a largedielectric anisotropy, a large specific resistance, a high stability toultraviolet light, a high stability to heat and a large elasticconstant. Another aim is to provide a liquid crystal composition havinga suitable balance regarding at least two of the characteristics.Another aim is to provide a liquid crystal display device including sucha composition. Another aim is to provide an AM device havingcharacteristics such as a short response time, a large voltage holdingratio, a low threshold voltage, a large contrast ratio and a longservice life.

Solution to Problem

The invention concerns a liquid crystal composition that has a positivedielectric anisotropy and contains at least one compound selected fromthe group of compounds represented by formula (1) as a first component,and at least one compound selected from the group of compoundsrepresented by formula (2) as a second component, and a liquid crystaldisplay device including the composition:

wherein, in formula (1) and formula (2), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which at least one piece of hydrogen is replaced by fluorineor chlorine; R³ is alkenyl having 2 to 12 carbons or alkenyl having 2 to12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine; rings A and B are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl ortetrahydropyran-2,5-diyl; Z¹, Z² and Z³ are independently a single bond,ethylene, vinylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy, and at least one of Z¹, Z² and Z³ isdifluoromethyleneoxy; X¹ and X² are independently hydrogen or fluorine;Y¹ is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and aand b are independently 0, 1 or 2.

The invention also concerns use of the liquid crystal composition in aliquid crystal display device.

Advantageous Effects of Invention

An advantage of the invention is a liquid crystal composition satisfyingat least one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of the nematic phase, a smallviscosity, a suitable optical anisotropy, a large dielectric anisotropy,a large specific resistance, a high stability to ultraviolet light, ahigh stability to heat and a large elastic constant. Another advantageis a liquid crystal composition having a suitable balance regarding atleast two of the characteristics. Another advantage is a liquid crystaldisplay device including such a composition. Another advantage is an AMdevice having characteristics such as a short response time, a largevoltage holding ratio, a low threshold voltage, a large contrast ratioand a long service life.

DESCRIPTION OF EMBODIMENTS

Usage of terms herein is as described below. Terms “liquid crystalcomposition” and “liquid crystal display device” may be occasionallyabbreviated as “composition” and “device,” respectively. “Liquid crystaldisplay device” is a generic term for a liquid crystal display panel anda liquid crystal display module. “Liquid crystal compound” is a genericterm for a compound having a liquid crystal phase such as a nematicphase and a smectic phase, and a compound having no liquid crystal phasebut to be mixed with a composition for the purpose of adjustingcharacteristics such as a temperature range of the nematic phase,viscosity and a dielectric anisotropy. The compound has a six-memberedring such as 1,4-cyclohexylene and 1,4-phenylene, and has rod-likemolecular structure. “Polymerizable compound” is a compound to be addedfor the purpose of forming a polymer in the composition. At least onecompound selected from the group of compounds represented by formula (1)may be occasionally abbreviated as “compound (1).” “Compound (1)” meansone compound or two or more compounds represented by formula (1). A samerule applies also to any other compound represented by any otherformula. An expression “at least one piece of” in the context of“replaced by” means that not only a position but also the number thereofcan be selected without restriction.

The liquid crystal composition is prepared by mixing a plurality ofliquid crystal compounds. A proportion (content) of the liquid crystalcompounds is expressed in terms of weight percent (% by weight) based onthe weight of the liquid crystal composition. An additive such as anoptically active compound, an antioxidant, an ultraviolet lightabsorber, a dye, an antifoaming agent, the polymerizable compound, apolymerization initiator and a polymerization inhibitor is added to thecomposition when necessary. A proportion (amount of addition) of theadditive is expressed in terms of weight percent (% by weight) based onthe weight of the liquid crystal composition in a manner similar to theproportion of the liquid crystal compound. Weight parts per million(ppm) may be occasionally used. A proportion of the polymerizationinitiator and the polymerization inhibitor is exceptionally expressedbased on the weight of the polymerizable compound.

“Maximum temperature of the nematic phase” may be occasionallyabbreviated as “maximum temperature.” “Minimum temperature of thenematic phase” may be occasionally abbreviated as “minimum temperature.”An expression “having a large specific resistance” means that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of the nematic phasein an initial stage, and the composition has the large specificresistance at room temperature and also at a temperature close to themaximum temperature of the nematic phase even after the device has beenused for a long period of time. An expression “having a large voltageholding ratio” means that the device has a large voltage holding ratioat room temperature and also at a temperature close to the maximumtemperature of the nematic phase in the initial stage, and the devicehas the large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of the nematic phase evenafter the device has been used for the long period of time.

An expression “at least one piece of ‘A’ may be replaced by ‘B’” meansthat the number of ‘A’ is arbitrary. When the number of ‘A’ is 1, aposition of ‘A’ is arbitrary, and also when the number of ‘A’ is 2 ormore, positions thereof can be selected without restriction. A same ruleapplies also to an expression “at least one piece of ‘A’ is replaced by‘B’.”

A symbol of terminal group R¹ is used for a plurality of compounds inchemical formulas of component compounds. In the compounds, two groupsrepresented by two pieces of arbitrary R¹ may be identical or different.In one case, for example, R¹ of compound (1) is ethyl and R¹ of compound(1-1) is ethyl. In another case, for example, R¹ of compound (1) isethyl and R¹ of compound (1-1) is propyl. A same rule applies also to asymbol of R⁴ or the like. In formula (3), when c is 2, two of rings Cexists. In the compound, two rings represented by two of rings C may beidentical or different. A same rule applies also to two of arbitraryrings C when C is larger than 2. A same rule applies also to a symbol ofZ¹, ring E or the like.

Then, 2-fluoro-1,4-phenylene means two divalent groups described below.In a chemical formula, fluorine may be leftward (L) or rightward (R). Asame rule applies also to a divalent group of asymmetrical ring such astetrahydropyran-2,5-diyl.

The invention includes the items described below.

Item 1. A liquid crystal composition that has a positive dielectricanisotropy and contains at least one compound selected from the group ofcompounds represented by formula (1) as a first component, and at leastone compound selected from the group of compounds represented by formula(2) as a second component:

wherein, in formula (1) and formula (2), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which at least one piece of hydrogen is replaced by fluorineor chlorine; R³ is alkenyl having 2 to 12 carbons or alkenyl having 2 to12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine; rings A and B are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl ortetrahydropyran-2,5-diyl; Z¹, Z² and Z³ are independently a single bond,ethylene, vinylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy, and at least one of Z¹, Z² and Z³ isdifluoromethyleneoxy; X¹ and X² are independently hydrogen or fluorine;Y¹ is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and aand b are independently 0, 1 or 2.

Item 2. The liquid crystal composition according to item 1, containingat least one compound selected from the group of compounds representedby formulas (1-1) to (1-5) as the first component:

wherein, in formula (1-1) to formula (1-5), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; X¹ and X² are independently hydrogen or fluorine; Y¹ isfluorine, chlorine, alkyl having 1 to 12 carbons in which at least onepiece of hydrogen is replaced by fluorine or chlorine, alkoxy having 1to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.

Item 3. The liquid crystal composition according to item 1 or 2, whereina proportion of the first component is in the range of 3% by weight to40% by weight, and a proportion of the second component is in the rangeof 10% by weight to 70% by weight, based on the weight of the liquidcrystal composition.

Item 4. The liquid crystal composition according to any one of items 1to 3, further containing at least one compound selected from the groupof compounds represented by formula (3) as a third component:

wherein, in formula (3), R⁴ and R⁵ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which at least one pieceof hydrogen is replaced by fluorine or chlorine; ring C and ring D areindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 2,5-difluoro-1,4-phenylene; Z⁴ is a single bond, ethylene orcarbonyloxy; c is 1, 2 or 3; in which, when c is 1, ring D is1,4-phenylene.

Item 5. The liquid crystal composition according to any one of items 1to 4, containing at least one compound selected from the group ofcompounds represented by formulas (3-1) to (3-12) as the thirdcomponent:

wherein, in formula (3-1) to formula (3-12), R⁴ and R⁵ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.

Item 6. The liquid crystal composition according to item 4 or 5, whereina proportion of the third component is in the range of 5% by weight to40% by weight based on the weight of the liquid crystal composition.

Item 7. The liquid crystal composition according to any one of items 1to 6, further containing at least one compound selected from the groupof compounds represented by formula (4) as a fourth component:

wherein, in formula (4), R⁶ is alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, or alkenyl having 2 to 12 carbons; ring E is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1, 3-dioxane-2, 5-diyl or tetrahydropyran-2,5-diyl;Z⁵ is a single bond, ethylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy; X³ and X⁴ are independently hydrogen or fluorine;Y² is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and dis 1, 2, 3 or 4.

Item 8. The liquid crystal composition according to any one of items 1to 7, containing at least one compound selected from the group ofcompounds represented by formulas (4-1) to (4-34) as the fourthcomponent:

wherein, in formula (4-1) to formula (4-34), R⁶ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons.

Item 9. The liquid crystal composition according to item 7 or 8, whereina proportion of the fourth component is in the range of 15% by weight to80% by weight based on the weight of the liquid crystal composition.

Item 10. The liquid crystal composition according to any one of items 1to 9, containing at least one compound selected from the group ofcompounds represented by formula (5) as a fifth component:

wherein, in formula (5), R⁷ and R⁸ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyloxy having 2 to 12 carbons; ring G and ring K areindependently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,1,4-phenylene in which at least one piece of hydrogen is replaced byfluorine or chlorine, or tetrahydropyran-2,5-diyl; ring J is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z⁶ and Z⁷ are independently a singlebond, ethylene, carbonyloxy or methyleneoxy; e is 1, 2 or 3, and f is 0or 1; and a sum of e and f is 3 or less.

Item 11. The liquid crystal composition according to anyone of items 1to 10, containing at least one compound selected from the group ofcompounds represented by formulas (5-1) to (5-21) as the fifthcomponent:

wherein, in formula (5-1) to formula (5-21), R⁷ and R⁸ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons or alkenyloxy having 2 to 12 carbons.

Item 12. The liquid crystal composition according to item 10 or 11,wherein a proportion of the fifth component is in the range of 3% byweight to 25% by weight based on the weight of the liquid crystalcomposition.

Item 13. The liquid crystal composition according to any one of items 1to 12, wherein a maximum temperature of a nematic phase is 70° C. orhigher, an optical anisotropy (measured at 25° C.) at a wavelength of589 nanometers is 0.07 or more and a dielectric anisotropy (measured at25° C.) at a frequency of 1 kHz is 2 or more.

Item 14. A liquid crystal display device, including the liquid crystalcomposition according to anyone of items 1 to 13.

Item 15. The liquid crystal display device according to item 14, whereinan operating mode in the liquid crystal display device includes a TNmode, an ECB mode, an OCB mode, an IPS mode, an FFS mode or an FPA mode,and a driving mode in the liquid crystal display device includes anactive matrix mode.

Item 16. Use of the liquid crystal composition according to any one ofitems 1 to 13 in a liquid crystal display device.

The invention further includes the following items: (a) the composition,further containing at least one of additives such as an optically activecompound, an antioxidant, an ultraviolet light absorber, a dye, anantifoaming agent, a polymerizable compound, a polymerization initiatoror a polymerization inhibitor; (b) an AM device including thecomposition; (c) the composition further containing a polymerizablecompound, and a polymer sustained alignment (PSA) mode AM deviceincluding the composition; (d) a polymer sustained alignment (PSA) modeAM device, wherein the device includes the composition, and apolymerizable compound in the composition is polymerized; (e) a deviceincluding the composition and having the PC mode, the TN mode, the STNmode, the ECB mode, the OCB mode, the IPS mode, the VA mode, the FFSmode or the FPA mode; (f) a transmissive device including thecomposition; (g) use of the composition as the composition having thenematic phase; and (h) use as an optically active composition by addingthe optically active compound to the composition.

The composition of the invention will be described in the followingorder. First, a constitution of the component compounds in thecomposition will be described. Second, main characteristics of thecomponent compounds and main effects of the compounds on the compositionwill be described. Third, a combination of components in thecomposition, a preferred proportion of the components and the basisthereof will be described. Fourth, a preferred embodiment of thecomponent compounds will be described. Fifth, a preferred componentcompounds will be described. Sixth, an additive that may be added to thecomposition will be described. Seventh, methods for synthesizing thecomponent compounds will be described. Last, an application of thecomposition will be described.

First, the constitution of the component compounds in the compositionwill be described. The composition of the invention is classified intocomposition A and composition B. Composition A may further contain anyother liquid crystal compound, an additive or the like in addition tothe liquid crystal compound selected from compound (1), compound (2),compound (3), compound (4) and compound (5). An expression “any otherliquid crystal compound” means a liquid crystal compound different fromcompound (1), compound (2), compound (3), compound (4) and compound (5).Such a compound is mixed with the composition for the purpose of furtheradjusting the characteristics. The additive is the optically activecompound, the antioxidant, the ultraviolet light absorber, the dye, theantifoaming agent, the polymerizable compound, the polymerizationinitiator, the polymerization inhibitor or the like.

Composition B consists essentially of liquid crystal compounds selectedfrom compound (1), compound (2), compound (3), compound (4) and compound(5). An expression “essentially” means that the composition may containthe additive, but contains no any other liquid crystal compound.Composition B has a smaller number of components than composition A has.Composition B is preferred to composition A in view of cost reduction.

Composition A is preferred to composition B in view of possibility offurther adjusting the characteristics by mixing any other liquid crystalcompound.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of the composition willbe described. The main characteristics of the component compounds aresummarized in Table 2 on the basis of advantageous effects of theinvention. In Table 2, a symbol L stands for “large” or “high,” a symbolM stands for “medium” and a symbol S stands for “small” or “low.” Thesymbols L, M and S represent a classification based on a qualitativecomparison among the component compounds, and 0 (zero) means “a value isnearly zero.”

TABLE 2 Characteristics of Compounds Compounds (1) (2) (3) (4) (5)Maximum temperature S to L M S to L S to L S to M Viscosity M to L S Sto M M to L M Optical anisotropy M to L S S to L M to L M to LDielectric anisotropy S to L 0 0 S to L M to L¹⁾ Specific resistance L LL L L ¹⁾A value of dielectric anisotropy is negative, and the symbolshows magnitude of an absolute value.

Upon mixing the component compounds with the composition, the maineffects of the component compounds on the characteristics of thecomposition are as described below. Compound (1) increases thedielectric anisotropy. Compound (2) decreases the viscosity. Compound(3) increases the maximum temperature or decreases the minimumtemperature. Compound (4) increases the dielectric anisotropy anddecreases the minimum temperature. Compound (5) increases the dielectricconstant in a minor axis direction.

Third, the combination of components in the composition, the preferredproportion of the component compounds and the basis thereof will bedescribed. A preferred combination of components in the compositionincludes a combination of the first component and the second component,a combination of the first component, the second component and the thirdcomponent, a combination of the first component, the second componentand the fourth component, a combination of the first component, thesecond component and the fifth component, a combination of the firstcomponent, the second component, the third component and the fourthcomponent, a combination of the first component, the second component,the third component and the fifth component, a combination of the firstcomponent, the second component, the fourth component and the fifthcomponent, or a combination of the first component, the secondcomponent, the third component, the fourth component and the fifthcomponent. A further preferred combination of components includes acombination of the first component, the second component and the thirdcomponent, a combination of the first component, the second componentand the fourth component, or a combination of the first component, thesecond component, the third component and the fourth component.

A preferred proportion of the first component is approximately 3% byweight or more for increasing the dielectric anisotropy, andapproximately 40% by weight or less for decreasing the viscosity. Afurther preferred proportion is in the range of approximately 3% byweight to approximately 35% by weight. A particularly preferredproportion is in the range of approximately 5% by weight toapproximately 30% by weight.

A preferred proportion of the second component is approximately 10% byweight or more for decreasing the viscosity, and approximately 70% byweight or less for increasing the dielectric anisotropy. A furtherpreferred proportion is in the range of approximately 10% by weight toapproximately 60% by weight. A particularly preferred proportion is inthe range of approximately 15% by weight to approximately 50% by weight.

A preferred proportion of the third component is approximately 5% byweight or more for increasing the maximum temperature or decreasing theviscosity, and approximately 40% by weight or less for increasing thedielectric anisotropy. A further preferred proportion is in the range ofapproximately 5% by weight to approximately 35% by weight. Aparticularly preferred proportion is in the range of approximately 5% byweight to approximately 30% by weight.

A preferred proportion of the fourth component is approximately 15% byweight or more for increasing the dielectric anisotropy, andapproximately 80% by weight or less for decreasing the minimumtemperature. A further preferred proportion is in the range ofapproximately 20% by weight to approximately 75% by weight. Aparticularly preferred proportion is in the range of approximately 25%by weight to approximately 70% by weight.

A preferred proportion of the fifth component is approximately 3% byweight or more for increasing the dielectric anisotropy, andapproximately 25% by weight or less for decreasing the minimumtemperature. A further preferred proportion is in the range ofapproximately 5% by weight to approximately 20% by weight. Aparticularly preferred proportion is in the range of approximately 5% byweight to approximately 15% by weight.

Fourth, the preferred embodiment of the component compounds will bedescribed. R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons. Preferred R¹ is alkyl having1 to 12 carbons for increasing the stability to ultraviolet light orheat. R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons,alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons inwhich at least one piece of hydrogen is replaced by fluorine orchlorine. Preferred R² is alkyl having 1 to 12 carbons for increasingthe stability to ultraviolet light or heat. R³ is alkenyl having 2 to 12carbons or alkenyl having 2 to 12 carbons in which at least one piece ofhydrogen is replaced by fluorine or chlorine. Preferred R³ is alkenylhaving 2 to 12 carbons for decreasing the viscosity. R⁴ and R⁵ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which at least one piece of hydrogen is replaced by fluorineor chlorine. Preferred R⁴ or R⁵ is alkenyl having 2 to 12 carbons fordecreasing the viscosity, and alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat. R⁶ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having2 to 12 carbons. Preferred R⁶ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat. R⁷ and R⁸ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyloxy having 2 to 12carbons. Preferred R⁷ or R⁸ is alkyl having 1 to 12 carbons forincreasing the stability, and alkoxy having 1 to 12 carbons forincreasing the dielectric anisotropy.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Furtherpreferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A preferred configuration of —CH═CH— in thealkenyl depends on a position of a double bond. Trans is preferred inalkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyland 3-hexenyl for decreasing the viscosity, for instance. Cis ispreferred in alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thealkenyl, straight-chain alkenyl is preferred to branched-chain alkenyl.

Preferred alkenyloxy is vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxyor 4-pentenyloxy. Further preferred al kenyloxy is allyloxy or3-butenyloxy for decreasing the viscosity.

Preferred examples of alkenyl in which at least one piece of hydrogen isreplaced by fluorine or chlorine include 2,2-difluorovinyl,3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenylor 6,6-difluoro-5-hexenyl. Further preferred examples include2,2-difluorovinyl or 4,4-difluoro-3-butenyl for decreasing theviscosity.

Rings A and B are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl ortetrahydropyran-2,5-diyl. Preferred ring A or B is 1,4-phenylene or2-fluoro-1,4-phenylene for increasing the optical anisotropy. Ring C andring D are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene. Preferred ring Cor ring D is 1,4-cyclohexylene for decreasing the viscosity, or1,4-phenylene for increasing the optical anisotropy. Ring E is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.Preferred ring E is 1,4-phenylene or 2-fluoro-1,4-phenylene forincreasing the optical anisotropy. Ring G and ring K are independently1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene inwhich at least one piece of hydrogen is replaced by fluorine orchlorine, or tetrahydropyran-2,5-diyl. Preferred examples of“1,4-phenylene in which at least one piece of hydrogen is replaced byfluorine or chlorine” include 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene or 2-chloro-3-fluoro-1,4-phenylene. Preferredring G or ring K is 1,4-cyclohexylene for decreasing the viscosity,tetrahydropyran-2,5-diyl for increasing the dielectric anisotropy, and1,4-phenylene for increasing the optical anisotropy. Ring J is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl. Preferred ring J is2,3-difluoro-1,4-phenylene for increasing the dielectric anisotropy.With regard to the configuration of 1,4-cyclohexylene, trans ispreferred to cis for increasing the maximum temperature. With regard tothe configuration of 1,4-cyclohexylene, trans is preferred to cis forincreasing the maximum temperature. Tetrahydropyran-2,5-diyl includes:

preferably

Z¹, Z² and Z³ are independently a single bond, ethylene, vinylene,acetylene, methyleneoxy, carbonyloxy or difluoromethyleneoxy, and atleast one of Z¹, Z² and Z³ is difluoromethyleneoxy. Preferred Z¹, Z² orZ³ is a single bond for decreasing the viscosity, anddifluoromethyleneoxy for increasing the dielectric anisotropy. Z⁴ is asingle bond, ethylene or carbonyloxy. Preferred Z⁴ is a single bond fordecreasing the viscosity. Z⁵ is a single bond, ethylene, acetylene,methyleneoxy, carbonyloxy or difluoromethyleneoxy. Preferred Z⁴ is asingle bond for decreasing the viscosity, and difluoromethyleneoxy forincreasing the dielectric anisotropy. Z⁶ and Z⁷ are independently asingle bond, ethylene, carbonyloxy or methyleneoxy. Preferred Z⁶ or Z⁷is a single bond for decreasing the viscosity, and methyleneoxy forincreasing the dielectric anisotropy.

X¹ and X² are independently hydrogen or fluorine. Preferred X¹ or X² isfluorine for increasing the dielectric anisotropy.

Y¹ is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or al kenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.Preferred Y¹ is fluorine for decreasing the minimum temperature. Y² isfluorine, chlorine, alkyl having 1 to 12 carbons in which at least onepiece of hydrogen is replaced by fluorine or chlorine, alkoxy having 1to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.Preferred Y² is fluorine for decreasing the minimum temperature.

Then, a and b are independently 0, 1 or 2. Preferred a is 1 or 2 forincreasing the maximum temperature. Preferred b is 0 for decreasing theviscosity, and 1 for decreasing the minimum temperature. Then, c is 1, 2or 3. Preferred c is 1 for decreasing the viscosity, and 2 or 3 forincreasing the maximum temperature. Then, d is 1, 2, 3 or 4. Preferred dis 2 for decreasing the minimum temperature, and 3 for increasing thedielectric anisotropy. Then, e is 1, 2 or 3, f is 0 or 1, and a sum of eand f is 3 or less. Preferred e is 1 for decreasing the viscosity, and 2or 3 for increasing the maximum temperature. Preferred f is 0 fordecreasing the viscosity, and 1 for decreasing the minimum temperature.

Fifth, the preferred component compounds will be described. Preferredcompound (1) includes compound (1-1) to compound (1-5) described in item2. In the compounds, at least one of the first components preferablyincludes compound (1-2), compound (1-3) or compound (1-4).

Preferred compound (3) includes compound (3-1) to compound (3-12)described in item 5. In the compounds, at least one of the thirdcomponents preferably includes compound (3-2), compound (3-4), compound(3-5), compound (3-6), compound (3-8) or compound (3-12). At least twoof the third components preferably includes a combination of compound(3-2) and compound (3-4), a combination of compound (3-2) and compound(3-5) or a combination of compound (3-2) and compound (3-6).

Preferred compound (4) includes compound (4-1) to compound (4-34)described in item 8. In the compounds, at least one of the fourthcomponents preferably includes compound (4-4), compound (4-12), compound(4-14), compound (4-15), compound (4-17), compound (4-18), compound(4-23), compound (4-27), compound (4-28) or compound (4-29). At leasttwo of the fourth components preferably includes a combination ofcompound (4-12) and compound (4-15), a combination of compound (4-14)and compound (4-27), a combination of compound (4-18) and compound(4-24), a combination of compound (4-18) and compound (4-28), acombination of compound (4-24) and compound (4-28), or a combination ofcompound (4-28) and compound (4-29).

Preferred compound (5) includes compound (5-1) to compound (5-21)described in item 11. In the compounds, at least one of the fifthcomponents preferably includes compound (5-1), compound (5-3), compound(5-4), compound (5-6), compound (5-8) or compound (5-10). At least twoof the fifth components preferably includes a combination of compound(5-1) and compound (5-6), a combination of compound (5-1) and compound(5-10), a combination of compound (5-3) and compound (5-6), acombination of compound (5-3) and compound (5-10), a combination ofcompound (5-4) and compound (5-6), or a combination of compound (5-4)and compound (5-8).

Sixth, the additive that may be added to the composition will bedescribed. Such an additive includes the optically active compound, theantioxidant, the ultraviolet light absorber, the dye, the antifoamingagent, the polymerizable compound, the polymerization initiator, thepolymerization inhibitor or the like. The optically active compound isadded to the composition for inducing a helical structure in a liquidcrystal to give a twist angle. Examples of such a compound includecompound (6-1) to compound (6-5). A preferred proportion of theoptically active compound is approximately 5% by weight or less. Afurther preferred proportion is in the range of approximately 0.01% byweight to approximately 2% by weight.

The antioxidant is added to the composition for preventing a decrease inthe specific resistance caused by heating in air, or for maintaining alarge voltage holding ratio at room temperature and also at thetemperature close to the maximum temperature after the device has beenused for a long period of time. Preferred examples of the antioxidantinclude compound (7) where t is an integer from 1 to 9 or the like.

In compound (7), preferred t is 1, 3, 5, 7 or 9. Further preferred t is7. Compound (7) where t is 7 is effective for maintaining the largevoltage holding ratio at room temperature and also at the temperatureclose to the maximum temperature even after the device has been used fora long period of time because the compound (7) has a small volatility. Apreferred proportion of the antioxidant is approximately 50 ppm or morefor achieving an effect thereof, and approximately 600 ppm or less foravoiding a decrease in the maximum temperature or an increase in theminimum temperature. A further preferred proportion is in the range ofapproximately 100 ppm to approximately 300 ppm.

Preferred examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also preferred. A preferred proportion of the absorber or thestabilizer is approximately 50 ppm or more for achieving an effectthereof, and approximately 10,000 ppm or less for avoiding the decreasein the maximum temperature or avoiding the increase in the minimumtemperature. A further preferred proportion is in the range ofapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is added tothe composition for the purpose of adapting the composition to a devicehaving a guest host (GH) mode. A preferred proportion of the dye is inthe range of approximately 0.01% by weight to approximately 10% byweight. The antifoaming agent such as dimethyl silicone oil or methylphenyl silicone oil is added to the composition for preventing foamformation. A preferred proportion of the antifoaming agent isapproximately 1 ppm or more for achieving an effect thereof, andapproximately 1,000 ppm or less for avoiding a poor display. A furtherpreferred proportion is in the range of approximately 1 ppm toapproximately 500 ppm.

The polymerizable compound is added to the composition for the purposeof adapting the composition to a device having the polymer sustainedalignment (PSA) mode. Preferred examples of polymerizable compoundsinclude a compound having a polymerizable group such as acrylate,methacrylate, a vinyl compound, a vinyloxy compound, propenyl ether, anepoxy compound (oxirane, oxetane) and vinyl ketone. Further preferredexamples include an acrylate derivative or a methacrylate derivative. Apreferred proportion of the polymerizable compound is approximately0.05% by weight or more for achieving an effect thereof, andapproximately 10% or less for avoiding a poor display. A furtherpreferred proportion is in the range of approximately 0.1% by weight toapproximately 2% by weight. The polymerizable compound is polymerized byirradiation with ultraviolet light. The polymerizable compound may bepolymerized in the presence of an initiator such as aphotopolymerization initiator. Suitable conditions for polymerization,suitable types of the initiator and suitable amounts thereof are knownto those skilled in the art and are described in literature. Forexample, Irgacure 651 (registered trademark; BASF), Irgacure 184(registered trademark; BASF) or Darocur 1173 (registered trademark;BASF), each being a photoinitiator, is suitable for radicalpolymerization. A preferred proportion of the photopolymerizationinitiator is in the range of approximately 0.1% by weight toapproximately 5% by weight based on the total weight of thepolymerizable compound. A further preferred proportion is in the rangeof approximately 1% by weight to approximately 3% by weight basedthereon.

Upon storing the polymerizable compound, the polymerization inhibitormay be added thereto for preventing polymerization. The polymerizablecompound is ordinarily added to the composition without removing thepolymerization inhibitor. Examples of the polymerization inhibitorinclude hydroquinone and a hydroquinone derivative such asmethylhydroquinone, 4-tert-butylcatechol, 4-methoxyphenol orphenothiazine.

Seventh, the methods for synthesizing the component compounds will bedescribed. The compounds can be prepared according to known methods.Examples of the synthetic methods are described. Compound (1) isprepared by the method described in JP H10-204016 A. Compound (2) isprepared by the method described in JP S59-176221 A. Compound (3-1) isprepared by the method described in JP S56-68636 A. Compound (4-2) andcompound (4-8) are prepared by the method described in JP H2-233626 A.Compound (5-1) and compound (5-6) are prepared by the method describedin JP H2-503441 A. The antioxidant is commercially available. A compoundwhere t in formula (7) is 1 can be obtained from Sigma-AldrichCorporation. A compound where t in compound (7) is 7 or the like can beprepared according to a method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described can be preparedaccording to methods described in books such as Organic Syntheses (JohnWiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.),Comprehensive Organic Synthesis (Pergamon Press) and New ExperimentalChemistry Course (Shin Jikken Kagaku Koza in Japanese) (Maruzen Co.,Ltd.). The composition is prepared according to publicly known methodsusing the thus obtained compounds. For example, the component compoundsare mixed and dissolved in each other by heating.

Last, the application of the composition will be described. Thecomposition of the invention mainly has a minimum temperature ofapproximately −10° C. or lower, a maximum temperature of approximately70° C. or higher, and an optical anisotropy in the range ofapproximately 0.07 to approximately 0.20. A device including thecomposition has the large voltage holding ratio. The composition issuitable for use in the AM device. The composition is particularlysuitable for use in a transmissive AM device. The composition having anoptical anisotropy in the range of approximately 0.08 to approximately0.25 may be prepared by controlling the proportion of the componentcompounds or by mixing any other liquid crystal compound, and furtherthe composition having an optical anisotropy in the range ofapproximately 0.10 to approximately 0.30 may be prepared. Thecomposition can be used as the composition having the nematic phase, andas the optically active composition by adding the optically activecompound.

The composition can be used for the AM device. The composition can alsobe used for a PM device. The composition can also be used for an AMdevice and a PM device each having a mode such as the PC mode, the TNmode, the STN mode, the ECB mode, the OCB mode, the IPS mode, the FFSmode, the VA mode and the FPA mode. Use for the AM device having the TNmode, the OCB mode, the IPS mode or the FFS mode is particularlypreferred. In the AM device having the IPS mode or the FFS mode,alignment of liquid crystal molecules when no voltage is applied may beparallel or vertical to a glass substrate. The device may be of areflective type, a transmissive type or a transflective type. Use forthe transmissive device is preferred. Use for an amorphous silicon-TFTdevice or a polycrystal silicon-TFT device is allowed. The compositioncan also be used for a nematic curvilinear aligned phase (NCAP) deviceprepared by microencapsulating the composition, or for a polymerdispersed (PD) device in which a three-dimensional network-polymer isformed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

The invention will be described in greater detail by way of Examples.However, the invention is not limited by the Examples. The inventionincludes a mixture of a composition in Example 1 and a composition inExample 2. The invention also includes a mixture in which at least twocompositions in Examples are mixed. The thus prepared compound wasidentified by methods such as an NMR analysis. Characteristics of thecompound and the composition were measured by methods described below.

NMR analysis: For measurement, DRX-500 made by Bruker BioSpinCorporation was used. In ¹H-NMR measurement, a sample was dissolved in adeuterated solvent such as CDCl₃, and measurement was carried out underconditions of room temperature, 500 MHz and 16 times of accumulation.Tetramethylsilane (TMS) was used as an internal standard. In ¹⁹F-NMRmeasurement, CFCl₃ was used as an internal standard, and measurement wascarried out under conditions of 24 times of accumulation. In explainingnuclear magnetic resonance spectra obtained, s, d, t, q, quin, sex and mstand for a singlet, a doublet, a triplet, a quartet, a quintet, asextet and a multiplet, and br being broad, respectively.

Gas chromatographic analysis: GC-14B Gas Chromatograph made by ShimadzuCorporation was used for measurement. A carrier gas was helium (2 mL/perminute). A sample vaporizing chamber and a detector (FID) were set to280° C. and 300° C., respectively. A capillary column DB-1 (length 30 m,bore 0.32 mm, film thickness 0.25 μm; dimethylpolysiloxane as astationary phase, non-polar) made by Agilent Technologies, Inc. was usedfor separation of component compounds. After the column was kept at 200°C. for 2 minutes, the column was heated to 280° C. at a rate of 5° C.per minute. A sample was prepared in an acetone solution (0.1% byweight), and then 1 microliter of the solution was injected into thesample vaporizing chamber. A recorder was C-R5A Chromatopac made byShimadzu Corporation or the equivalent thereof. The resulting gaschromatogram showed a retention time of a peak and a peak areacorresponding to each of the component compounds.

As a solvent for diluting the sample, chloroform, hexane or the like mayalso be used. The following capillary columns may also be used forseparating component compounds: HP-1 (length 30 m, bore 0.32 mm, filmthickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1 (length 30m, bore 0.32 mm, film thickness 0.25 μm) made by Restek Corporation andBP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by SGEInternational Pty. Ltd. A capillary column CBP1-M50-025 (length 50 m,bore 0.25 mm, film thickness 0.25 μm) made by Shimadzu Corporation mayalso be used for the purpose of avoiding an overlap of peaks of thecompounds.

A proportion of liquid crystal compounds contained in the compositionmay be calculated by the method as described below. The mixture ofliquid crystal compounds is detected by gas chromatograph (FID). An arearatio of each peak in the gas chromatogram corresponds to the ratio(weight ratio) of the liquid crystal compound. When the capillarycolumns described above were used, a correction coefficient of each ofthe liquid crystal compounds may be regarded as 1 (one). Accordingly,the proportion (% by weight) of the liquid crystal compound iscalculated from the area ratio of each peak.

Sample for measurement: When characteristics of a composition wasmeasured, the composition was used as a sample as was. Upon measuringcharacteristics of a compound, a sample for measurement was prepared bymixing the compound (15% by weight) with a base liquid crystal (85% byweight). Values of characteristics of the compound were calculated,according to an extrapolation method, using values obtained bymeasurement. (Extrapolated value)={(measured value of a sample formeasurement)−0.85×(measured value of a base liquid crystal)}/0.15. Whena smectic phase (or crystals) precipitates at the ratio thereof at 25°C., a ratio of the compound to the base liquid crystal was changed stepby step in the order of (10% by weight: 90% by weight), (5% by weight:95% by weight) and (1% by weight: 99% by weight). Values of maximumtemperature, optical anisotropy, viscosity and dielectric anisotropywith regard to the compound were determined according to theextrapolation method.

Abase liquid crystal described below was used. A proportion of thecomponent compound was expressed in terms of weight percent (% byweight).

24%

36%

25%

15%

Measuring method: Measurement of characteristics was carried out by themethods described below. Most of the measuring methods are applied asdescribed in the Standard of the Japan Electronics and InformationTechnology Industries Association (hereinafter abbreviated as JEITA)(JEITA EIAJ ED-2521B) discussed and established by JEITA, or modifiedthereon. No thin film transistor (TFT) was attached to a TN device usedfor measurement.

(1) Maximum temperature of nematic phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope, and heated at a rate of 1° C. per minute. Temperature whenpart of the sample began to change from a nematic phase to an isotropicliquid was measured.

(2) Minimum temperature of nematic phase (T_(c); ° C.): Samples eachhaving a nematic phase were put in glass vials and kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then liquid crystal phases were observed. For example, whenthe sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., T_(c) of the sample wasexpressed as T_(c)<−20° C.

(3) Viscosity (bulk viscosity; η; measured at 20° C.; mPa·S): Acone-plate (E type) rotational viscometer made by Tokyo Keiki, Inc. wasused for measurement.

(4) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·S):Measurement was carried out according to a method described in M. Imaiet al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995).A sample was put in a TN device in which a twist angle was 0 degrees anda distance (cell gap) between two glass substrates was 5 micrometers.Voltage was applied stepwise to the device in the range of 16 V to 19.5V at an increment of 0.5V. After a period of 0.2 second with no voltageapplication, voltage was repeatedly applied under conditions of only onerectangular wave (rectangular pulse; 0.2 second) and no voltageapplication (2 seconds). A peak current and a peak time of a transientcurrent generated by the applied voltage were measured. A value ofrotational viscosity was obtained from the measured values andcalculation equation (8) on page 40 of the paper presented by M. Imai etal. A value of dielectric anisotropy required for the calculation wasdetermined using the device with which the rotational viscosity wasmeasured and by the method described below.

(5) Optical anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (n∥) was measured when a direction of polarized light was parallelto a direction of rubbing. A refractive index (n⊥) was measured when thedirection of polarized light was perpendicular to the direction ofrubbing. A value of optical anisotropy was calculated from an equation:

Δn=n∥−n⊥.

(6) Dielectric anisotropy (Δ∈; measured at 25° C.): A sample was put ina TN device in which a distance (cell gap) between two glass substrateswas 9 micrometers and a twist angle was 80 degrees. Sine waves (10 V, 1kHz) were applied to the device, and after 2 seconds, a dielectricconstant (∈∥) in a major axis direction of the liquid crystal moleculeswas measured. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (∈⊥) in a minor axis direction ofthe liquid crystal molecules was measured. A value of dielectricanisotropy was calculated from an equation: Δ∈=∈∥−E⊥.

(7) Threshold voltage (Vth; measured at 25° C.; V): An LCD-5100luminance meter made by Otsuka Electronics Co., Ltd. was used formeasurement. A light source was a halogen lamp. A sample was put in anormally white mode TN device in which a distance (cell gap) between twoglass substrates was 0.45/Δn (μm) and a twist angle was 80 degrees. Avoltage (32 Hz, rectangular waves) to be applied to the device wasstepwise increased from 0 V to 10 V at an increment of 0.02 V. On theoccasion, the device was irradiated with light from a directionperpendicular to the device, and an amount of light transmitted throughthe device was measured. A voltage-transmittance curve was prepared, inwhich the maximum amount of light corresponds to 100% transmittance andthe minimum amount of light corresponds to 0% transmittance. A thresholdvoltage is expressed in terms of a voltage at 90% transmittance.

(8) Voltage holding ratio (VHR-1; measured at 25° C.; %): A TN deviceused for measurement had a polyimide alignment film, and a distance(cell gap) between two glass substrates was 5 micrometers. A sample wasput in the device, and the device was sealed with an ultraviolet-curableadhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TNdevice and the device was charged. A decaying voltage was measured for16.7 milliseconds with a high-speed voltmeter, and area A between avoltage curve and a horizontal axis in a unit cycle was determined. AreaB is an area without decay. A voltage holding ratio is expressed interms of a percentage of area A to area B.

(9) Voltage holding ratio (VHR-2; measured at 80° C.; %): A voltageholding ratio was measured according to procedures identical with theprocedures described above except that measurement was carried out at80° C. in place of 25° C. The thus obtained value was expressed in termsof VHR-2.

(10) Voltage holding ratio (VHR-3; measured at 25° C.; %): Stability toultraviolet light was evaluated by measuring a voltage holding ratioafter a device was irradiated with ultraviolet light. A TN device usedfor measurement had a polyimide alignment film and a cell gap was 5micrometers. A sample was injected into the device, and then the devicewas irradiated with light for 20 minutes. A light source was an ultrahigh-pressure mercury lamp USH-500D (made by Ushio, Inc.), and adistance between the device and the light source was 20 centimeters. Inmeasurement of VHR-3, a decaying voltage was measured for 16.7milliseconds. A composition having large VHR-3 has a large stability toultraviolet light. A value of VHR-3 is preferably 90% or more, andfurther preferably, 95% or more.

(11) Voltage holding ratio (VHR-4; measured at 25° C.; %): Stability toheat was evaluated by measuring a voltage holding ratio after a TNdevice into which a sample was injected was heated in aconstant-temperature bath at 80° C. for 500 hours. In measurement ofVHR-4, a decaying voltage was measured for 16.7 milliseconds. Acomposition having large VHR-4 has a large stability to heat.

(12) Response time (τ; measured at 25° C.; ms): An LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used for measurement. Alight source was a halogen lamp. A low-pass filter was set at 5 kHz. Asample was put in a normally white mode TN device in which a distance(cell gap) between two glass substrates was 5.0 micrometers and a twistangle was 80 degrees. A voltage (rectangular waves; 60 Hz, 5V, 0.5second) was applied to the device. On the occasion, the device wasirradiated with light from a direction perpendicular to the device, andan amount of light transmitted through the device was measured, in whichthe maximum amount of light corresponds to 100% transmittance, and theminimum amount of light corresponds to 0% transmittance. A rise time(τr; millisecond) was expressed in terms of time required for a changefrom 90% transmittance to 10% transmittance. A fall time (τf;millisecond) was expressed in terms of time required for a change from10% transmittance to 90% transmittance. A response time was representedby a sum of the rise time and the fall time thus obtained.

(13) Elastic constant (K; measured at 25° C.; pN): HP4284A LCR Metermade by Yokogawa-Hewlett-Packard Co. was used for measurement. A samplewas put in a horizontal alignment device in which a distance (cell gap)between two glass substrates was 20 micrometers. An electric charge of 0V to 20 V was applied to the device, and electrostatic capacity andapplied voltage were measured. The measured values of electrostaticcapacity (C) and applied voltage (V) were fitted to equation (2.98) andequation (2.101) on page 75 of “Liquid Crystal Device Handbook” (EkishoDebaisu Handobukku in Japanese; The Nikkan Kogyo Shimbun, Ltd.) andvalues of K11 and K33 were obtained from equation (2.99). Next, K22 wascalculated using the previously determined values of K11 and K33 inequation (3.18) on page 171. Elastic constant K was expressed in termsof a mean value of the thus determined K11, K22 and K33.

(14) Specific resistance (p; measured at 25 C; Ωcm): Into a vesselequipped with electrodes, 1.0 milliliter of a sample was injected. Adirect current voltage (10 V) was applied to the vessel, and a directcurrent after 10 seconds was measured: Specific resistance wascalculated from the following equation: (specificresistance)={(voltage)×(electric capacity of the vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

(15) Helical pitch (P; measured at room temperature; μm): A helicalpitch was measured according to a wedge method. Refer to page 196 in“Handbook of Liquid Crystals (Ekisho Binran in Japanese)” (issued in2000, Maruzen Co., Ltd.). A sample was injected into a wedge cell andleft to stand at room temperature for 2 hours, and then a gap (d2−d1)between disclination lines was observed by a polarizing microscope(trade name: MM40/60 Series, Nikon Corporation). A helical pitch (P) wascalculated according to the following equation in which an angle of thewedge cell was expressed as θ:

P=2×(d2−d1)×tan θ.

(16) Dielectric constant (∈⊥; measured at 25° C.) in a minor axisdirection: A sample was put in a TN device in which a distance (cellgap) between two glass substrates was 9 micrometers and a twist anglewas 80 degrees. Sine waves (0.5 V, 1 kHz) were applied to the device,and after 2 seconds, a dielectric constant (∈⊥) in a minor axisdirection of the liquid crystal molecules was measured.

The compounds described in Examples were described using symbolsaccording to definitions in Table 3 below. In Table 3, the configurationof 1,4-cyclohexylene is trans. A parenthesized number next to asymbolized compound in Examples corresponds to the number of thecompound. A symbol (-) means any other liquid crystal compound. Aproportion (percentage) of the liquid crystal compound is expressed interms of weight percent (% by weight) based on the weight of the liquidcrystal composition. Values of the characteristics of the compositionwere summarized in the last part.

TABLE 3 Method for Description of Compounds using Symbols R—(A₁)—Z₁— . .. Z—(A_(n))—R′ 1) Left-terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— F—C_(n)H_(2n)— Fn— 2) Right-terminal Group —R′ Symbol—C_(n)H_(2n+1) -n —OC_(n)N_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1)—Vn —C_(n)H_(2n)—CH═CH₂ —nV —C_(n)H_(2n)—CH═CH—C_(m)H_(2n+1) —nVm—CH═CF₂ —VFF —COOCH₃ —EMe —F —F —Cl —CL —OCF₃ —OCF3 —CF₃ —CF3 —CN —C 3)Bonding Group —Z_(n)— Symbol —C_(n)H_(2n)— n —COO— E —CH═CH— V —C≡C— T—CF₂O— X —CH₂O— 1O 4) Ring Structure —A_(n)— Symbol

H

Dh

dh

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

G

Py

B(2F,3F) 5) Examples of Description Example 1. 3-HH—V1

Example 2. 3-HHB—Cl

Example 3. 4-GB(F)B(F,F)XB(F,F)—F

Example 4. 3-HVHXB(F,F)—F

Example 1

3-HHVHXB(F,F)-F (1-2) 5% 3-HH-V (2) 27% 3-HH-V1 (2) 3% V-HHB-1 (3-4) 7%3-HHXB(F,F)-F (4-4) 6% 3-HBB(F,F)-F (4-8) 11% 3-BB(F)B(F,F)-F (4-15) 3%3-BB(F,F)XB(F,F)-F (4-18) 17% 2-HHBB(F,F)-F (4-19) 4% 3-HHBB(F,F)-F(4-19) 4% 4-HHBB(F,F)-F (4-19) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 10% NI =85.4° C.; T_(c) < −30° C.; η = 15.3 mPa · s; Δn = 0.111; Δε = 10.2; Vth= 1.34 V; γ1 = 88.2 mPa · s.

Comparative Example 1

The composition in Example 1 contains compound (1) being the firstcomponent. For comparison, a composition in which compound (1) being thefirst component in Example 1 was replaced by a compound being the fourthcomponent similar to compound (1) was taken as Comparative Example 1.

3-HH-V (2) 27% 3-HH-V1 (2) 3% V-HHB-1 (3-4) 7% 3-HHXB(F,F)-F (4-4) 6%3-HBB(F,F)-F (4-8) 11% 3-BB(F)B(F,F)-F (4-15) 3% 3-BB(F,F)XB(F,F)-F(4-18) 17% 2-HHBB(F,F)-F (4-19) 4% 3-HHBB(F,F)-F (4-19) 4% 4-HHBB(F,F)-F(4-19) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 10% 3-HHHXB(F,F)-F (4) 5% NI =85.5° C.; T_(c) < 0° C.; η = 15.4 mPa · s; Δn = 0.111; Δε = 10.2; Vth =1.33 V; γ1 = 91.8 mPa · s.

Example 2

3-HHVHXB(F,F)-F (1-2) 10% 3-HH-V (2) 22% 3-HH-V1 (2) 3% V-HHB-1 (3-4) 7%3-HHXB(F,F)-F (4-4) 6% 3-HBB(F,F)-F (4-8) 11% 3-BB(F)B(F,F)-F (4-15) 3%3-BB(F,F)XB(F,F)-F (4-18) 17% 2-HHBB(F,F)-F (4-19) 4% 3-HHBB(F,F)-F(4-19) 4% 4-HHBB(F,F)-F (4-19) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 10% NI =97.0° C.; T_(c) < −30° C.; η = 18.3 mPa · s; Δn = 0.115; Δε = 11.2; Vth= 1.35 V; γ1 = 114.5 mPa · s.

Example 3

2-HVHXB(F,F)-F (1-1) 7% 3-HVHXB(F,F)-F (1-1) 7% 4-HVHXB(F,F)-F (1-1) 7%3-HH-V (2) 18% 3-HH-V1 (2) 10% 2-BB(F)B-2V (3-6) 3% 3-HHEBH-3 (3-10) 4%5-HXB(F,F)-F (4-1) 3% 3-GHB(F,F)-F (4-7) 4% 3-HBB(F,F)-F (4-8) 11%3-HBEB(F,F)-F (4-10) 5% 3-BB(F)B(F,F)-F (4-15) 3% 3-BB(F,F)XB(F,F)-F(4-18) 7% 3-BB(F)B(F,F)XB(F,F)-F (4-28) 4% 4-BB(F)B(F,F)XB(F,F)-F (4-28)4% 2O-B(2F,3F)BXB(F,F)-F (4-32) 3% NI = 80.8° C.; T_(c) < −20° C.; η =11.4 mPa · s; Δn = 0.105; Δε = 9.8; Vth = 1.39 V; γ1 = 65.7 mPa · s.

Example 4

2-HVHXB(F,F)-F (1-1) 5% 3-HVHXB(F,F)-F (1-1) 5% 4-HVHXB(F,F)-F (1-1) 5%3-HHVHXB(F,F)-F (1-2) 5% 3-HH-V (2) 10% 3-HH-V1 (2) 7% 1-BB-5 (3-2) 3%3-HHEBH-5 (3-10) 3% 3-HHEB(F,F)-F (4-3) 4% 1-HHXB(F,F)-F (4-4) 4%3-HHXB(F,F)-F (4-4) 10% 3-HBB(F,F)-F (4-8) 8% 3-GB(F)B(F)-F (4-11) 4%3-GB(F)B(F,F)-F (4-12) 5% 3-BB(F,F)XB(F,F)-F (4-18) 10% 3-GBB(F)B(F,F)-F(4-22) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 9% NI = 89.2° C.; T_(c) < −20°C.; η = 20.0 mPa · s; Δn = 0.109; Δε = 12.2; Vth = 1.30 V; γ1 = 115.2mPa · s.

Example 5

3-HVHXB(F)-CF3 (1-1) 3% 2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2)5% 1V2-HH-2V1 (2) 4% 3-HH-V (2) 13%  3-HH-V1 (2) 10%  1-BB-3 (3-2) 7%V-HHB-1 (3-4) 4% 5-B(F)BB-3 (3-7) 3% 3-HHXB(F,F)-CF3 (4-5) 7%5-GHB(F,F)-F (4-7) 3% 3-GB(F,F)XB(F,F)-F (4-14) 10%  2-HHBB(F,F)-F(4-19) 4% 3-HHBB(F,F)-F (4-19) 4% 4-HHBB(F,F)-F (4-19) 3%5-BB(F)B(F,F)XB(F,F)-F (4-28) 5% 3-BB(2F,3F)XB(F,F)-F (4-31) 4%3-HB(2F,3F)BXB(F,F)-F (4-33) 3% 2-HH-3 (—) 3% NI = 97.5° C.; T_(c) <−20° C.; η = 16.1 mPa · s; Δn = 0.110; Δ∈ = 9.4; Vth = 1.42 V; γ1 = 92.7mPa · s.

Example 6

3-HHVHXB(F,F)-F (1-2) 5% 4-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-CF3(1-2) 3% 2-HVHBXB(F,F)-F (1-3) 3% 3-HH-V (2) 15%  4-HH-V (2) 8% 3-HH-V1(2) 5% 3-HB-O2 (3-1) 3% V-HHB-1 (3-4) 3% 3-HHXB(F,F)-F (4-4) 8%2-HBB(F,F)-F (4-8) 4% 3-HBB(F,F)-F (4-8) 6% 5-HBB(F,F)-F (4-8) 6%2-HBEB(F,F)-F (4-10) 5% 3-BB(F)B(F,F)-F (4-15) 5% 2-HHB(F)B(F,F)-F(4-20) 4% 3-HHB(F)B(F,F)-F (4-20) 5% 3-GB(F)B(F)B(F)-F (4-21) 3%3-HBB(F,F)XB(F,F)-F (4-24) 4% NI = 105.6° C.; T_(c) < −20° C.; η = 15.8mPa · s; Δn = 0.107; Δ∈ = 8.5; Vth = 1.45 V; γ1 = 91.0 mPa · s.

Example 7

3-HHVHXB(F,F)-F (1-2) 7% 3-HVHBXB(F,F)-F (1-3) 3% 4-HVHBXB(F,F)-F (1-3)3% 3-HH-V (2) 18%  3-HH-V1 (2) 3% 7-HB-1 (3-1) 3% 2-BB(F)B-3 (3-6) 3%3-HGB(F,F)-F (4-6) 3% 5-HGB(F,F)-F (4-6) 3% 3-HB(F)B(F,F)-F (4-9) 4%5-HB(F)B(F,F)-F (4-9) 3% 3-GB(F,F)XB(F)-F (4-13) 5% 3-GB(F,F)XB(F,F)-F(4-14) 5% 3-BB(F,F)XB(F,F)-F (4-18) 17%  2-HHBB(F,F)-F (4-19) 4%3-HHBB(F,F)-F (4-19) 4% 4-HHBB(F,F)-F (4-19) 3% 3-BB(F)B(F,F)XB(F,F)-F(4-28) 5% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 4% NI = 85.2° C.; T_(c) < −20°C.; η = 22.0 mPa · s; Δn = 0.114; Δ∈ = 13.4; Vth = 1.22 V; γ1 = 126.7mPa · s.

Example 8

3-HVHXB(F,F)-F (1-1) 5% 2-HVHB(F,F)XB(F,F)-F (1-4) 3%3-HVHB(F,F)XB(F,F)-F (1-4) 3% 4-HVHB(F,F)XB(F,F)-F (1-4) 3% 3-HH-V (2)17%  3-HH-V1 (2) 10%  1-BB-3 (3-2) 5% 5-HBB(F)B-3 (3-12) 3%3-HHXB(F,F)-F (4-4) 16%  3-BB(F)B(F,F)-CF3 (4-16) 3% 3-BBXB(F,F)-F(4-17) 5% 3-HBB(F,F)XB(F,F)-F (4-24) 9% 4-GB(F)B(F,F)XB(F)-F (4-26) 5%3-GB(F)B(F,F)XB(F,F)-F (4-27) 5% 5-BB(F)B(F,F)XB(F,F)-F (4-28) 5% 3-HH-4(—) 3% NI = 93.0° C.; T_(c) < −20° C.; η = 13.6 mPa · s; Δn = 0.114; Δ∈= 12.6; Vth = 1.28 V; γ1 = 78.3 mPa · s.

Example 9

2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2) 10%  3-HH-V (2) 18% 3-HH-V1 (2) 12%  3-HHB-3 (3-4) 3% V-HBB-3 (3-5) 3% 3-HHXB(F,F)-F (4-4)12%  3-HBB(F,F)-F (4-8) 10%  3-HBEB(F,F)-F (4-10) 3% 5-HBEB(F,F)-F(4-10) 4% 3-dhBB(F,F)XB(F,F)-F (4-25) 6% 3-GB(F)B(F,F)XB(F,F)-F (4-27)4% 4-GB(F)B(F,F)XB(F,F)-F (4-27) 5% 3-BB(2F,3F)BXB(F,F)-F (4-34) 5% NI =111.1° C.; T_(c) < −20° C.; η = 16.4 mPa · s; Δn = 0.107; Δ∈ = 10.8; Vth= 1.34 V; γ1 = 94.5 mPa · s.

Example 10

2-HVHXB(F,F)-F (1-1) 5% 3-HVHXB(F,F)-F (1-1) 5% 2-HHVHXB(F,F)-F (1-2) 5%3-HHVHXB(F,F)-F (1-2) 5% 3-HH-V (2) 15%  3-HH-V1 (2) 12%  3-HB-O2 (3-1)3% 3-HHEH-3 (3-3) 5% 3-HHB(F,F)-F (4-2) 3% 4-HHB(F,F)-F (4-2) 3%5-HHB(F,F)-F (4-2) 3% 3-BB(F,F)XB(F,F)-F (4-18) 14%  2-HHBB(F,F)-F(4-19) 4% 4-HHBB(F,F)-F (4-19) 4% 4-HHB(F)B(F,F)-F (4-20) 4%3-HBBXB(F,F)-F (4-23) 5% 3-BB(F,F)XB(F)B(F,F)-F (4-29) 5% NI = 103.8°C.; T_(c) < −20° C.; η = 16.3 mPa · s; Δn = 0.102; Δ∈ = 9.3; Vth = 1.42V; γ1 = 93.9 mPa · s.

Example 11

2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2) 5% 4-HHVHXB(F,F)-F (1-2)5% 3-HH-V (2) 18%  3-HH-V1 (2) 5% 5-HB-O2 (3-1) 3% 3-HBB-2 (3-5) 3%2-HHEB(F,F)-F (4-3) 4% 3-HBB(F,F)-F (4-8) 5% 5-HBB(F,F)-F (4-8) 5%V-HB(F)B(F,F)-F (4-9) 3% 5-GB(F)B(F,F)-F (4-12) 4% 3-BB(F,F)XB(F,F)-F(4-18) 15%  2-HHBB(F,F)-F (4-19) 2% 3-HHBB(F,F)-F (4-19) 3%4-HHBB(F,F)-F (4-19) 3% 4-GB(F)B(F,F)XB(F)-F (4-26) 5%3-BB(F)B(F,F)XB(F,F)-F (4-28) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 4% NI =96.6° C.; T_(c) < −20° C.; η = 22.1 mPa · s; Δn = 0.113; Δ∈ = 11.8; Vth= 1.33 V; γ1 = 127.3 mPa · s.

Example 12

3-HHVHXB(F,F)-F (1-2) 5% 2-HVHBXB(F,F)-F (1-3) 5% 3-HVHBXB(F,F)-F (1-3)5% 3-HH-V (2) 10%  5-HH-V (2) 5% 3-HH-V1 (2) 10%  5-B(F)BB-2 (3-7) 3%3-HB(F)HH-2 (3-9) 2% 5-HBB(F)B-2 (3-12) 3% 3-HHXB(F,F)-F (4-4) 10% 4-GHB(F,F)-F (4-7) 3% 3-HBB(F,F)-F (4-8) 9% 3-BB(F)B(F,F)-F (4-15) 3%3-BB(F,F)XB(F,F)-F (4-18) 10%  2-HHBB(F,F)-F (4-19) 2% 3-HHBB(F,F)-F(4-19) 3% 4-HHBB(F,F)-F (4-19) 3% 3-BB(F)B(F,F)XB(F,F)-F (4-28) 3%5-BB(F)B(F,F)XB(F)B(F,F)-F (4-30) 3% 3-B(2F,3F)BXB(F,F)-F (4-32) 3% NI =105.3° C.; T_(c) < −20° C.; η = 20.9 mPa · s; Δn = 0.120; Δ∈ = 10.3; Vth= 1.34 V; γ1 = 120.4 mPa · s.

Example 13

2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2) 5% 1-HH-2V1 (2) 4% 3-HH-V(2) 15%  3-HH-VFF (2) 3% 3-HHB-1 (3-4) 3% 2-BB(F)B-5 (3-6) 3%3-HHXB(F,F)-F (4-4) 15%  3-HBB(F,F)-F (4-8) 11%  3-BB(F,F)XB(F,F)-F(4-18) 17%  2-HHBB(F,F)-F (4-19) 4% 3-HHBB(F,F)-F (4-19) 4%4-HHBB(F,F)-F (4-19) 3% 5-GB(F)B(F,F)XB(F,F)-F (4-27) 5%5-BB(F)B(F,F)XB(F,F)-F (4-28) 3% NI = 96.3° C.; T_(c) < −20° C.; η =20.4 mPa · s; Δn = 0.112; Δ∈ = 11.7; Vth = 1.31 V; γ1 = 117.5 mPa · s.

Example 14

3-HHVHXB(F,F)-F (1-2) 5% 4-HHVHXB(F,F)-F (1-2) 5% 3-HH-V (2) 10% 3-HH-V1 (2) 10%  V-HBB-2 (3-5) 3% 1-BB(F)B-2V (3-6) 3% 3-HHXB(F,F)-F(4-4) 10%  3-HBB(F,F)-F (4-8) 10%  3-BB(F)B(F,F)-F (4-15) 5%3-BB(F,F)XB(F,F)-F (4-18) 15%  2-HHBB(F,F)-F (4-19) 3% 3-HHBB(F,F)-F(4-19) 3% 4-HHBB(F,F)-F (4-19) 3% 3-BB(F)B(F,F)XB(F,F)-F (4-28) 4%4-BB(F)B(F,F)XB(F,F)-F (4-28) 6% 3-HBB(2F,3F)-O2 (5-10) 5% NI = 103.1°C.; T_(c) < −20° C.; η = 22.1 mPa · s; Δn = 0.130; Δ∈ = 11.2; Vth = 1.35V; γ1 = 127.3 mPa · s.

Example 15

3-HHVHXB(F,F)-F (1-2) 7% 4-HHVHXB(F,F)-F (1-2) 5% 3-HH-V (2) 17% 3-HH-V1 (2) 10%  V2-BB-1 (3-2) 3% 3-HHB-O1 (3-4) 3% 3-HHXB(F,F)-F (4-4)12%  2-HBB(F,F)-F (4-8) 5% 3-HBB(F,F)-F (4-8) 6% 3-BB(F,F)XB(F,F)-F(4-18) 10%  2-HHBB(F,F)-F (4-19) 3% 3-HHBB(F,F)-F (4-19) 3%4-HHBB(F,F)-F (4-19) 4% 2-dhBB(F,F)XB(F,F)-F (4-25) 3%4-BB(F)B(F,F)XB(F,F)-F (4-28) 6% 1O1-HBBH-3 (—) 3% NI = 107.7° C.; T_(c)< −20° C.; η = 16.4 mPa · s; Δn = 0.110; Δ∈ = 9.3; Vth = 1.42 V; γ1 =94.5 mPa · s.

Example 16

2-HHVHXB(F,F)-F (1-2) 6% 3-HHVHXB(F,F)-F (1-2) 6% 4-HHVHXB(F,F)-F (1-2)6% 3-HH-V (2) 27%  V2-HHB-1 (3-4) 3% 3-HHEBH-4 (3-10) 3% 3-HHB(F,F)-F(4-2) 5% 5-HGB(F,F)-F (4-6) 5% 3-HBB(F,F)-F (4-8) 4% 3-BB(F,F)XB(F,F)-F(4-18) 9% 3-HHBB(F,F)-F (4-19) 5% 3-GB(F)B(F)B(F)-F (4-21) 5%2-HBB(F,F)XB(F,F)-F (4-24) 6% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 10%  NI =115.9° C.; T_(c) < −20° C.; η = 21.4 mPa · s; Δn = 0.114; Δ∈ = 10.7; Vth= 1.34 V; γ1 = 123.3 mPa · s.

Example 17

2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2) 10%  3-HH-V (2) 22% 3-HH-V1 (2) 8% VFF-HHB-1 (3-4) 3% VFF2-HHB-1 (3-4) 3% V-HHB-1 (3-4) 3%1-HHXB(F,F)-F (4-4) 3% 3-HHXB(F,F)-F (4-4) 5% 2-HBB(F,F)-F (4-8) 3%3-HBB(F,F)-F (4-8) 3% 5-HBB(F,F)-F (4-8) 5% 3-BB(F,F)XB(F,F)-F (4-18)15%  3-BB(F)B(F,F)XB(F,F)-F (4-28) 3% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 5%5-BB(F)B(F,F)XB(F,F)-F (4-28) 4% NI = 93.8° C.; T_(c) < −20° C.; η =12.6 mPa · s; Δn = 0.107; Δ∈ = 10.2; Vth = 1.35 V; γ1 = 72.6 mPa · s.

Example 18

3-HVHXB(F,F)-F (1-1) 5% 2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2)5% 3-HH-2V1 (2) 5% 3-HH-V (2) 10%  4-HH-V (2) 10%  3-HHEH-5 (3-3) 3%V2-BB2B-1 (3-8) 3% 3-HHXB(F,F)-F (4-4) 10%  3-HBB(F,F)-F (4-8) 5%5-HBB(F,F)-F (4-8) 5% 3-BB(F)B(F,F)-F (4-15) 4% 3-BB(F,F)XB(F,F)-F(4-18) 7% 2-HHBB(F,F)-F (4-19) 5% 3-HHBB(F,F)-F (4-19) 4%4-GBB(F)B(F,F)-F (4-22) 4% 4-BB(F)B(F,F)XB(F,F)-F (4-28) 10%  NI =106.6° C.; T_(c) < −20° C.; η = 22.2 mPa · s; Δn = 0.117; Δ∈ = 10.3; Vth= 1.35 V; γ1 = 127.9 mPa · s.

Example 19

2-HHVHXB(F,F)-F (1-2) 5% 3-HHVHXB(F,F)-F (1-2) 5% 4-HHVHXB(F,F)-F (1-2)5% 3-HH-V (2) 20%  1V2-BB-1 (3-2) 3% 5-HB(F)BH-3 (3-11) 3% 3-HHXB(F,F)-F(4-4) 10%  3-HBB(F,F)-F (4-8) 6% 3-BB(F)B(F,F)-F (4-15) 3%3-BB(F,F)XB(F,F)-F (4-18) 14%  3-HHBB(F,F)-F (4-19) 3% 4-HHBB(F,F)-F(4-19) 4% 5-HBB(F,F)XB(F,F)-F (4-24) 9% 4-BB(F)B(F,F)XB(F,F)-F (4-28)10%  NI = 104.6° C.; T_(c) < −20° C.; η = 23.7 mPa · s; Δn = 0.121; Δ∈ =12.7; Vth = 1.29 V; γ1 = 136.5 mPa · s.

The compositions in Example 1 to Example 19 had a lower minimumtemperature in comparison with the composition in Comparative Example 1.Accordingly, the liquid crystal composition according to the inventionis concluded to have superb characteristics.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

INDUSTRIAL APPLICABILITY

A liquid crystal composition of the invention satisfies at least one ofcharacteristics such as a high maximum temperature, a low minimumtemperature, a small viscosity, a suitable optical anisotropy, a largedielectric anisotropy, a large specific resistance, a large elasticconstant, a high stability to ultraviolet light and a high stability toheat, or has a suitable balance regarding at least two of thecharacteristics. A liquid crystal display device including thecomposition has a short response time, a large voltage holding ratio, alarge contrast ratio, a long service life and so forth, and thus can beused for a liquid crystal projector, a liquid crystal television and soforth.

What is claimed is:
 1. A liquid crystal composition that has a positivedielectric anisotropy and contains at least one compound selected fromthe group of compounds represented by formula (1) as a first component,and at least one compound selected from the group of compoundsrepresented by formula (2) as a second component:

wherein, in formula (1) and formula (2), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which at least one piece of hydrogen is replaced by fluorineor chlorine; R³ is alkenyl having 2 to 12 carbons or alkenyl having 2 to12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine; rings A and B are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl ortetrahydropyran-2,5-diyl; Z¹, Z² and Z³ are independently a single bond,ethylene, vinylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy, and at least one of Z¹, Z² and Z³ isdifluoromethyleneoxy; X¹ and X² are independently hydrogen or fluorine;Y¹ is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and aand b are independently 0, 1 or
 2. 2. The liquid crystal compositionaccording to claim 1, containing at least one compound selected from thegroup of compounds represented by formulas (1-1) to (1-5) as the firstcomponent:

wherein, in formula (1-1) to formula (1-5), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; X¹ and X² are independently hydrogen or fluorine; Y¹ isfluorine, chlorine, alkyl having 1 to 12 carbons in which at least onepiece of hydrogen is replaced by fluorine or chlorine, alkoxy having 1to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or al kenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.
 3. Theliquid crystal composition according to claim 1, wherein a proportion ofthe first component is in the range of 3% by weight to 40% by weight,and a proportion of the second component is in the range of 10% byweight to 70% by weight, based on the weight of the liquid crystalcomposition.
 4. The liquid crystal composition according to claim 1,further containing at least one compound selected from the group ofcompounds represented by formula (3) as a third component:

wherein, in formula (3), R⁴ and R⁵ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which at least one pieceof hydrogen is replaced by fluorine or chlorine; ring C and ring D areindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 2,5-difluoro-1,4-phenylene; Z⁴ is a single bond, ethylene orcarbonyloxy; c is 1, 2 or 3; in which, when c is 1, ring D is1,4-phenylene.
 5. The liquid crystal composition according to claim 4,containing at least one compound selected from the group of compoundsrepresented by formulas (3-1) to (3-12) as the third component:

wherein, in formula (3-1) to formula (3-12), R⁴ and R⁵ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine.
 6. Theliquid crystal composition according to claim 4, wherein a proportion ofthe third component is in the range of 5% by weight to 40% by weightbased on the weight of the liquid crystal composition.
 7. The liquidcrystal composition according to claim 1, further containing at leastone compound selected from the group of compounds represented by formula(4) as a fourth component:

wherein, in formula (4), R⁶ is alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, or alkenyl having 2 to 12 carbons; ring E is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;Z⁵ is a single bond, ethylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy; X³ and X⁴ are independently hydrogen or fluorine;Y² is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and dis 1, 2, 3 or
 4. 8. The liquid crystal composition according to claim 7,containing at least one compound selected from the group of compoundsrepresented by formulas (4-1) to (4-34) as the fourth component:

wherein, in formula (4-1) to formula (4-34), R⁶ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons.
 9. The liquid crystal composition according to claim 7, whereina proportion of the fourth component is in the range of 15% by weight to80% by weight based on the weight of the liquid crystal composition. 10.The liquid crystal composition according to claim 4, further containingat least one compound selected from the group of compounds representedby formula (4) as a fourth component:

wherein, in formula (4), R⁶ is alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, or alkenyl having 2 to 12 carbons; ring E is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;Z⁵ is a single bond, ethylene, acetylene, methyleneoxy, carbonyloxy ordifluoromethyleneoxy; X³ and X⁴ are independently hydrogen or fluorine;Y² is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone piece of hydrogen is replaced by fluorine or chlorine, alkoxy having1 to 12 carbons in which at least one piece of hydrogen is replaced byfluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which atleast one piece of hydrogen is replaced by fluorine or chlorine; and dis 1, 2, 3 or
 4. 11. The liquid crystal composition according to claim1, containing at least one compound selected from the group of compoundsrepresented by formula (5) as a fifth component:

wherein, in formula (5), R⁷ and R⁸ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyloxy having 2 to 12 carbons; ring G and ring K areindependently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,1,4-phenylene in which at least one piece of hydrogen is replaced byfluorine or chlorine, or tetrahydropyran-2,5-diyl; ring J is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z⁶ and Z⁷ are independently a singlebond, ethylene, carbonyloxy or methyleneoxy; e is 1, 2 or 3, and f is 0or 1; and a sum of e and f is 3 or less.
 12. The liquid crystalcomposition according to claim 11, containing at least one compoundselected from the group of compounds represented by formulas (5-1) to(5-21) as the fifth component:

wherein, in formula (5-1) to formula (5-21), R⁷ and R⁸ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons or alkenyloxy having 2 to 12 carbons.
 13. Theliquid crystal composition according to claim 11, wherein a proportionof the fifth component is in the range of 3% by weight to 25% by weightbased on the weight of the liquid crystal composition.
 14. The liquidcrystal composition according to claim 1, wherein a maximum temperatureof a nematic phase is 70° C. or higher, an optical anisotropy (measuredat 25° C.) at a wavelength of 589 nanometers is 0.07 or more and adielectric anisotropy (measured at 25° C.) at a frequency of 1 kHz is 2or more.
 15. A liquid crystal display device, including the liquidcrystal composition according to claim
 1. 16. The liquid crystal displaydevice according to claim 15, wherein an operating mode in the liquidcrystal display device includes a TN mode, an ECB mode, an OCB mode, anIPS mode, an FFS mode or an FPA mode, and a driving mode in the liquidcrystal display device includes an active matrix mode.